Protective helmets have been worn to protect a user from head injuries. Protective helmets have been used for many endeavors, including for participants in sports (e.g., football, baseball, lacrosse, racing, skiing), for commercial activities (e.g., construction) and for military personnel (e.g., pilots, soldiers). Prior art helmets have generally comprised a single layer which is rigidly secured to the head of a user.
U.S. Pat. No. 4,287,613, entitled “Headgear With Energy Absorbing and Sizing Means” disclosed a headgear of the type used by football players. The headgear included a web suspension means comprising looped straps held together by a cord that threads through the looped straps and is knotted. The web suspension means performed a sizing function and maintained the top of the wearer's head out of contact with the upper wall of the helmet shell. The ends of the straps were connected to an encircling band that was fastened at selected locations to the helmet shell.
U.S. Pat. No. 5,035,009, entitled “Protective Helmet and Liner” disclosed a protective helmet having a sheet of sound deadening material between impact force absorbing pad structures disposed on the interior of the protective helmet.
Recent advances in helmets include U.S. Pat. No. 6,826,509, entitled “System And Method For Measuring The Linear And Rotational Acceleration Of A Body Part.” The '509 patent discloses a system using accelerometers to collect, record and process head acceleration data. See FIG. 7 of the '509 patent. See also the related U.S. Pat. No. 7,526,389.
U.S. Pat. No. 7,954,177 entitled “Sports Helmet” disclosed a sports helmet having ear flaps and jaw flaps.